import java.util.Scanner;

	class GradeCal
	{
		
	public static void main(String[] args) 
	{
			
	 String grade;
			
	int mark;
		Scanner sc=new Scanner(System.in);
			 
	System.out.print(" Input mark :  ");
			
	 
	mark =sc.nextInt();
			  
	if(mark>100) grade="YOUR MARK OVER FLOW";
			
	else if(mark>=80) grade="A";
			
	else if(mark>=75) grade="B+";

	else if(mark>=70) grade="B";
			
	else if(mark>=65) grade="C+";
			
	else if(mark>=60) grade="C";
			
	else if(mark>=55) grade="D+";
			
	else if(mark>=50) grade="D";
			
	else if(mark<0) grade="YOUR MARK UNDER FLOW";
			
	else grade="F";	
			
	System.out.println("Mark = "+mark+"  Grade = "+grade);
			
	}
}
